Radome gutter

ABSTRACT

A gutter carried on the exterior surface of a radome, above the radome low look antenna aperture for diverting water flow from the surface area of the aperture.

34 .4372, OR 3569978 SR [72] Inventor Lewis V. Smith 554,274 2/1896 Keiser 52/13X Bethesda, Md. 691,744 1/1902 Carr 52/11 [21] AppLNo. 757,373 874,510 12/1907 Johnston 52/11 [22] Filed Sept. 4, 1968 883,632 3/1908 Feyler 52/12X [45] Patented Mar. 9, 1971 1,362,755 12/1920 Stafler 52/11X [73] Assignee CommunicationsSatelllteCorporafion 1,630,839 5/1927 Fisher et a1. 61/14 2,978,704 4/1961 Cohen et a1 52/81X 3,209,499 10/1965 Koe 52/ 13 1 RADPME GUTTFR 3,250,024 5/1966 Douthitt m1... 52/2x s 2 3,355,895 12/1967 Bayeset a1.... 1/14 [52] U.S.(l 343 372 3,420,022 l/1969 Brock 52/309X 52/1 1 FOREIGN PATENTS 1 1' Int-CI H0111 U 2, 1,049,931 1/1954 France 52/12 E04d 13/00 50 Field ofSearch 52/11,2, i csuthefland 8 0 2 14. 72 AS81810!!! Examiner-Sam D. Bl-ll'kC, 111

Attorney-Sughrue,Rothwell,Mion,Zinn and Mac Peak [56} ReferencesCited UNITED STATES PATENTS 167,565 8/1952 Feld (Design) 52/80X ABSTRACT: A gutter carried on-the exterior surface of a 2,624,299 1/1953 Beegle 52/16 radome, above the radome low look antenna aperture for 3,439,460 4/1969 Allen 52/81 diverting water flow from the surface area of the aperture.

PATENTEDHA'R 912m 3569878 FIG. I

FIG. 4

INVENTOR LEWIS V. SMITH ATTORNEYQ RADOME GU'I'IER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to earth station antenna radomes used for satellite communications operations and more particularly to the provision of a water flow diverting gutter for a radome operating within a snow or rain environment. The invention relates particularly to those radomes of the inflatable, spherical type employing a fixed or a small sweep angle antenna having a low look angle.

2. Description of the Prior Art In the satellite communication field, earth station antenna radomes have been employed which operate in the 3.9 MHz to 6.2MI-i2frequency range with the radomes being located geographically such that on a day-to-day basis, they are frequently operating in a snow or rain environment. The signal received from the satellite by the earth station antenna is degraded when snowor rain falls on the radome protecting the same. The degradation results form two different conditions. The

, first condition involves the film of water which forms on the radome surface which attenuates and scatters the signal. The second condition results from the streams of water which form between the seams of the radome. These streams are uniformly spaced and may act as a diffraction grating or parasitic antenna.

In contrast to some communication installations, with the earth antenna located some distance form the equator and with the satellite positioned above the equator, the earth antenna employed with the present invention looks at the equatorial satellite at a low look angle. With this low look antenna aperture or window, the water flow which collects on the upper portion of the radome passes through the antenna aperture.

SUMMARY OF THE INVENTION This invention is directed to means for changing the pattern of water flow on the surface of a radome to eliminate or reduce signal degradation. A single water flow diverting gutter is placed'on the outer surface of the radome, above the line of sight for a low look antenna to interrupt the flow of water and divert it around the antenna aperture and to further prevent the formation of large rivulets between the seams of the radome or water films in the front of the antenna aperture. For an inflatable, spherical radome, the single gutter may take the form of an elongated, curved tube adhesively coupled to the outer surface of the radome skin. A formed extruded plastic gutter triangularly shaped in cross section in one form,

has its base attached to the sidewall of the radome, for stability. For rigidity with minimum mass, this type of gutter may also consist of an outer impervious sheet covering a foamed core.

- BRIEF DESCRIPTION OF THE DRAWING FIG. I is a top plan view of a generally spherical, inflatable radome incorporating the single radome gutter of the present invention.

FIG. 2 is a front elevational view of the radome shown in FIG. 1.

FIG. 3 is a sectional, elevational view of a portion of the radome of FIG. 2 taken about lines 3-3.

FIG. 4 is a sectional, elevational view of a radome employing a gutter of alternate form.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawing the radome gutter of the present invention is particularly useful for inflatable radomes formed of a material which is relatively light weight and which does not adversely affect reception of the satellite signal by the earth station antenna. A typical inflatable radome of generally spherical configuration is shown at 19, being formed of low loss dielectric material such as I-lypalon coated dacron or nylon. A pressure slightly in excess of atmospheric maintains the radome 10 in inflated condition, surrounding an antenna (not shown). A typical radome may be about 200 feet in diameter.

The antenna used at one specific North American geographical location lies at 70 longitude and 45 latitude. As such, the antenna looks at an equatorial satellite located between 0 and 15 longitude. In this case, the antenna aperture which may vary in azimuth from an angle of 106.5 to 1 16 will fall between extreme limits as indicated by the dotted line antenna aperture positions 12 and 14, respectively Therefore, an appreciable portion of the precipitation falling onto the upper surface 16 of the radome, will flow in the direction of arrows 18 passing in front of or, over the antenna apertures 12 and 14 before reaching the ground 21. The invention is directed broadly to the provision of a single, unitary gutter which is located several feet above the aperture clearance as defined by lines 12 and 14, such that any precipitation which falls onto the outer surface of the radome above the antenna aperture flows down to the gutter 20 and then along it and is discharged as streams at each end 22 of the gutter. The gutter is curved inwardly and downwardly in a direction away from the center to facilitate precipitation run off and diversion of the same to both sides of the antenna.

The exact configurations of the gutter may vary, however, and as seen in FIG, 3 the gutter 20 may be formed as a unitary extrusion of plastic material. The cross-sectional configuration of the extruded gutter 20 is in the form of a hollow triangle having a central void space 23, an extended base 24, a shortened and steep upper sidewall 26, and a more inclined lower sidewall 28. The side wall 26 forms, in conjunction with the upper base extension 30, a trough-like area 32 which may readily catch the film of water 34 which is passing downwardly over the upper surface of the radome skin 16. While the amount of water which is momentarily captured by the gutter 20 is shown as being quite extensive, this is merely illustrative of the function of the gutter since, in actuality, the fact that the gutter 20 is curved downwardly to either side form the center as indicated in FIG. 2, readily causes the entrained water to flow to the sides of the radome and fall by gravity from the gutter ends 22. A suitable adhesive (not shown) may be preaffixed to the rear wall 36 of the gutter base 24 to permanently secure the gutter 20 in position on the outer surface of the radome. If desired, to increase the rigidity of the gutter 20 without materially increasing its weight, the interior 23 of the triangular shape extrusion 20 may comprise foamed plastic, in which case the sections 24, 26 and 28 act as a cover for the foam core.

FIG. 4 shows an alternative form for the gutter which may be easily positioned on an existing radome and readily affixed thereto. In this case, the radome 10' receives a radome gutter 20 in the form of a pipe 40 of plastic material which again, may may be readily curved from the center outwardly and downward to conform to the curved surface of the spherical radome I0 while allowing the captured water film 34' on the upper radome surface 16' to flow into the radome gutter interior, as indicated, through a single slot 42 or a series of Iongitudinally spaced slots-which extend through the upper surface of the plastic pipe 40. To initially place the radome gutter on the exterior surface of the radome, a series of lines or ropes 44 are inserted through specially formed opposed holes 46 formed in the plastic pipe 40 and a knot 48 is then tied in the bottom end of line 44. The line or lines are then thrown over the radome and the gutter is pulled up the surface 16 of the radome, to physically locate the flexible plastic pipe 30 in its proper position having downwardly bent ends in similar fashion to the embodiment shown in FIG. 2. Once in place, suitable plastic adhesive 50 may be employed to securely fix the radome gutter in position. The line or lines 44 may, if desired, be left coupled to the plastic gutter pipe 40 subsequent to the placement of the adhesive 50, between the pipe 40 and the outer surface of the radome. All precipitation falling on the upper surface 16 of the radome and which would normally flow down in front of the antenna aperture is caught by either gutter or 2b prior to reaching the ground. The only requirement is that the gutter must have sufficient depth and slope to carry ofi the precipitation fast enough so that an overflow condition will not occur, thus defeating its purpose by spilling the water over the edge of the gutter and in front of the antenna aperture. A gutter configured in the manner of the embodiment of FIG. 3 is capable of diverting any deposit of water on the upper surface of a radome of 210 feet in diameter, even during a 4 inch per hour rainfall.

With respect to the embodiment of FIG. 4, the plastic tube 40 may be formed of neoprene and may be positioned on the radome with a number of dacron ropes 44. Preferably, the radome contact surface is cleaned prior to applying the adhesive 50. If necessary, the neoprene tube may be spliced by inserting a smaller tube segment (not shown) into each segment of tube 40 prior to applying adhesive to the body contact area of the main tube proper. After installation, it is preferably to paint the neoprene tube with Hypalon. The adhesive 50 may comprise l-lypalon or RTV silicone rubber adhesive.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

1 claim:

1. In a radome antenna assembly including an antenna having a radiation pattern defining a low look antenna window having a lateral dimension and a radome formed of low loss dielectric material overlying as said antenna, the improvement comprising: a gutter having ends extending beyond the lateral dimension of said window carried by said radome for diverting precipitation runofi from the antenna window surface area to minimize RF losses.

2. The radome antenna assembly as claimed in claim 1' wherein said radome is inflatable, and is generally spherical in configuration and the end so said gutter are curved downwardly from the center thereof to insure against precipitation overflow.

3. The radome antenna assembly as claimed in claim 2 wherein said gutter is formed of a low loss dielectric material and is adhesively affixed to the radome. v

4. The radome antenna assembly as claimed in claim 1 wherein said gutter comprises a unitary plastic tube adhesively afiixed to the outer surface of said radome, and the upper surface of said tube is slotted longitudinally to allow the precipitation runoff to flow to the tube interior.

5. The radome assembly as claimed in claim 4 further including a plurality of ropes coupled to said tube for facilitating the initial positioning of the gutter on the exterior surface of the radome and supporting the gutter once the desired position has been reached. I

6. The radome antenna assembly as claimed in claim 5 wherein said unitary plastic tube is formed of neoprene, and said ropes are formed of dacron.

7. The radome antenna assembly as claimed in claim 2 wherein said gutter comprises a unitary, hollow plastic extrusion which is triangular in cross-sectional configuration whereby, precipitation runoff is readily capture between one side of the triangular extrusion and the opposed radome surface.

8. The radome antenna assembly as claimed in claim 2 wherein said gutter comprises a foamed, plastic core covered with a thin impervious plastic layer.

9. The radome antenna assemblyas claimed in claim 8 wherein said gutter is triangular in cross-sectional configuration. 

1. In a radome antenna assembly including an antenna having a radiation pattern defining a low look antenna window having a lateral dimension and a radome formed of low loss dielectric material overlying as said antenna, the improvement comprising: a gutter having ends extending beyond the lateral dimension of said window carried by said radome for diverting precipitation runoff from the antenna window surface area to minimize RF losses.
 2. The radome antenna assembly as claimed in claim 1 wherein said radome is inflatable, and is generally spherical in configuration and the end so said gutter are curved downwardly from the center thereof to insure against precipitation overflow.
 3. The radome antenna assembly as claimed in claim 2 wherein said gutter is formed of a low loss dielectric material and is adhesively affixed to the radome.
 4. The radome antenna assembly as claimed in claim 1 wherein said gutter comprises a unitary plastic tube adhesively affixed to the outer surface of said radome, and the upper surface of said tube is slotted longitudinally to allow the precipitation runoff to flow to the tube interior.
 5. The radome assembly as claimed in claim 4 further including a plurality of ropes coupled to said tube for facilitating the initiaL positioning of the gutter on the exterior surface of the radome and supporting the gutter once the desired position has been reached.
 6. The radome antenna assembly as claimed in claim 5 wherein said unitary plastic tube is formed of neoprene, and said ropes are formed of dacron.
 7. The radome antenna assembly as claimed in claim 2 wherein said gutter comprises a unitary, hollow plastic extrusion which is triangular in cross-sectional configuration whereby, precipitation runoff is readily capture between one side of the triangular extrusion and the opposed radome surface.
 8. The radome antenna assembly as claimed in claim 2 wherein said gutter comprises a foamed plastic core covered with a thin impervious plastic layer.
 9. The radome antenna assembly as claimed in claim 8 wherein said gutter is triangular in cross-sectional configuration. 